1. Technical Field
The present invention relates generally to a process for separating a wafer into individual dies and in particular to a process for scribing wafers containing magnetic head sliders. Still more particularly, the present invention provides a chemical scribing process to improve magnetic head slider yields.
2. Description of the Related Art
Magnetic storage systems are employed for storing large amounts of information and are typically utilized for long term storage in a data processing system, such as a work station or a personal computer. In particular, magnetic disk drive systems are employed to read and write information to and from magnetic disks. A magnetic head assembly and a slider are utilized in a magnetic disk system, such as a hard disk drive, and move relative to the surface of a magnetic disk in a hard disk drive.
It is well known that during operation, a magnetic head assembly in, for example, a hard disk drive, floats a very small distance above the magnetic recording medium (i.e., the hard disk), which is rotated at high speeds. These magnetic head assemblies include a electromagnetic head, such as a magnetic transducer, mounted on a movable arm to read or write information on the hard disk. The magnetic disk system moves the magnetic head to a desired radial position over the surface of the rotating hard disk, where the magnetic head reads or writes information. Typically, the magnetic head is integrally formed in a carrier called a "slider". A slider provides mechanical support for the magnetic head and the electrical connections between the magnetic head and the remainder of the magnetic disk system.
In particular, a slider for a hard disk drive is usually fabricated on a wafer. The substrate of a wafer on which a slider is fabricated typically is constructed of a hard ceramic material such as ferrite or Al.sub.2 O.sub.3 --TiC. The electronic devices, which make up the magnetic head assembly in a slider, are usually encapsulated in alumina (Al.sub.2 O.sub.3). A large number of sliders may be fabricated on a single wafer. The number of sliders that may be fabricated on a single wafer is determined by the wafer size, the size of the sliders, and the area required for breaking up the wafer into separate sliders. Typically, a wafer is scribed and then broken up into a number of separate sliders.
Currently while breaking the wafer into separate sliders, the wafer is sawed utilizing one or more rotating blades which may be stacked in a gang. Typically, scribe lines are first cut though the alumina on the wafer. A fine blade is normally employed to create these scribe lines. In separating the sliders, the substrate is then cut with a second coarser blade in view of the substrate's hardness. Mechanical scribing and slicing may cause chips and cracks in the alumina. Chips trapped between the blade and the substrate may damage the sliders and cracks reaching the electronic devices may render a particular slider unusable. Width, sidewall slope, and placement of scribe lines may also fluctuate as the blade heats up and wears. Consequently, current manufacturing techniques may result in losses, thereby reducing yield, typically as a result of cracks in the alumina reaching the electronic devices in the slider. In addition, increased manufacturing time is required for mechanical scribing and cutting. Therefore, an improved process for separating sliders from wafers and thereby increasing the yield is desirable.